Dual damascene process for carbon-based low-K materials

1. A method for forming a dual damascene structure in a carbon-based, low-K material, comprising the steps of: a. providing a semiconductor structure having a first metal pattern thereover; said first metal pattern having a first barrier layer thereon; b. forming an organic dielectric layer on said first barrier layer; c. forming a hard mask layer on said organic dielectric layer; d. forming a trench through said hard mask layer and into said organic dielectric layer; said trench having a bottom and sidewalls; e. forming a second barrier layer over said hard mask layer and on the bottom and sidewalls of said trench; f. forming a bottom anti-reflective coating layer over said second barrier layer; g. patterning said bottom anti-reflective coating layer, said second barrier layer, and said organic dielectric layer to form a via opening; said via opening having a bottom comprising said first barrier layer and having sidewalls; h. removing said bottom anti-reflective coating layer; i. removing said first barrier layer from said bottom of said via opening and said second barrier layer from said bottom of said trench; j. forming a third barrier layer on said bottom and sidewalls of said trench, on said sidewalls of said via opening, and on said first metal pattern through said via opening; and k. forming a metal plug in said trench and said via opening to form a damascene structure.

2. The method of claim 1 wherein said first metal pattern is composed of copper and said first barrier layer is composed of silicon nitride having a thickness of between about 300 Angstroms and 500 Angstroms.

3. The method of claim 1 wherein said organic dielectric layer has a value of K of less than 3.0.

4. The method of claim 1 wherein said organic dielectric layer comprises a material having a value of K less than 3.0 and having a thickness of between about 1600 Angstroms and 7000 Angstroms.

5. The method of claim 1 wherein said hard mask layer comprises silicon oxynitride having a thickness of between about 1000 Angstroms and 3000 Angstroms.

6. The method of claim 1 wherein said second barrier layer comprises Tantalum nitride having a thickness of between about 250 Angstroms and 350 Angstroms, and said third barrier layer comprises Tantalum nitride having a thickness of between about 300 Angstroms and 600 Angstroms.

7. The method of claim 1 wherein said via opening and said trench are filled with copper using an ECD process.

8. A method for forming a dual damascene structure in a carbon-based, low-K dielectric layer, comprising the steps of: a. providing a semiconductor structure having a first metal pattern thereover; said first metal pattern having a first barrier layer thereon; b. forming an organic dielectric layer on said first barrier layer; said dielectric layer having a value of K of less than 3.0; c. forming a hard mask layer on said organic dielectric layer; said hard mask layer comprising silicon oxynitride; d. forming a trench through said hard mask layer and into said organic dielectric layer; said trench having a bottom and sidewalls; e. forming a second on the bottom and sidewalls of said trench; said second barrier layer comprising tantalum nitride; f. forming a bottom anti-reflective coating layer over said second barrier layer; g. forming a photoresist mask over said bottom anti-reflective coating; h. patterning said bottom anti-reflective coating layer, said second barrier layer, and said organic dielectric layer to form a via opening; said bottom anti-reflective coating layer being etched using a N.sub.2 /H.sub.2 reactive ion etch; said second barrier layer being etched using a CF.sub.4 /Ar/O.sub.2 reactive in etch; said orgnic dielectric layer being etched using a N.sub.2 /O.sub.2 reactive ion etch, whereby said photoresist mask and said bottom anti-reflective coating layer are removed by the N.sub.2 /O.sub.2 etch srtep, and whereby the edge of said organic dielectric layer adjacent said via opening is protected from faceting by said second barrier layer; said via opening having a bottom comprising said first barrier layer and having sidewalls; i. removing said first barrier layer from said bottom of said via opening and said second barrier layer from said bottom of said trench; j. forming a third barrier layer on said bottom and sidewalls of said trench, on said sidewalls of said via opening, and on said first metal pattern through said via opening; and k. forming a metal plug in said trench and said via opening to form a damascene structure.

9. The method of claim 8 wherein said first barrier layer and said second barrier layer are removed using a CF.sub.4 /Ar/O.sub.2 chemistry.

10. The method of claim 8 wherein said first metal pattern is composed of copper and said first barrier layer is composed of silicon nitride having a thickness of between about 300 Angstroms and 500 Angstroms.

11. The method of claim 8 wherein said organic dielectric layer has a value of K less than 3.0 and a thickness of between about 1600 Angstroms and 7000 Angstroms.

12. The method of claim 8 wherein said hard mask layer has a thickness of between about 1000 Angstroms and 3000 Angstroms.

13. The method of claim 8 wherein said second barrier layer comprises Tantalum nitride having a thickness of between about 250 Angstroms and 350 Angstroms, and said third barrier layer comprises Tantalum nitride having a thickness of between about 300 Angstroms and 600 Angstroms.

14. The method of claim 8 wherein said via opening and said trench are filled with copper using an ECD process.